How can contamination of evidence be prevented during collection?

Preventing contamination of evidence during collection is crucial for maintaining its integrity and ensuring that it is admissible in court. The correct choice emphasizes the importance of separating items collected from different locations. When evidence is collected from different scenes, there's a risk that items could be mixed or cross-contaminated if they're not kept distinct from one another. Separating items collected from various locations ensures that each piece of evidence is preserved in its original state and context, helping to avoid any confusion during analysis or in a legal setting.

This approach also protects the chain of custody and enables investigators to trace the origin of evidence accurately. In contrast, using envelopes for storage, while helpful for protecting physical items, does not inherently prevent contamination during the actual collection process. Documenting evidence with a narrative style is important for record-keeping but does not address physical integrity during collection. Collecting evidence with bare hands is often discouraged as it increases the likelihood of contamination, as skin oils and dirt can transfer to the evidence. Thus, separating evidence from different locations is the most effective way to maintain its purity and reliability for investigative purposes.